38 Reviews—Geological Survey of Great Britain. 
Brief reference is made to the Tertiary igneous rocks of Mull, which 
comprise basaltic lavas, for the most part amygdaloidal, and intrusive 
sills of olivine-dolerite, that make strong features and possess columnar 
jointing. Dykes of Tertiary dolerite and basalt are numerous 
throughout the entire area; and these, which are described in some 
detail, include teschenites, tholeiites, andesitic pitchstone, and camp- 
tonite. Altogether, with the chapters on Old Red and Tertiary rocks, 
the petrographical portion of the memoir extends over eighty pages. 
The higher grounds on the mainland, though glaciated, are com- 
paratively free from superficial deposits, but evidence is given of the 
westerly seaward passage of an ice-sheet, which at one time filled the 
sounds and sea-lochs and overrode the outer islands, rising in Scarba 
and Jura in places to a greater height than any part of the mainland. 
Numerous small freshwater lochs occupying rock-basins owe their 
origin to the ice-erosion. 
Raised beaches indicate that the area has undergone periodic 
elevation since Glacial times to the extent of about 100 feet; but it 
is mentioned that the contour-lines, which are continued ‘‘to a depth 
of 200 feet below Ordnance datum level, show that the floors of the 
different sea-lochs, and of the Sounds of Luing, Shuna, and Seil are 
studded with basins which, were the land upheaved to the extent of 
200 feet, would form lochs much larger in area than any existing on 
the present land surface ”’ 
The inference is that the land was elevated to that extent or more 
during the Glacial period, and subsequently depressed, so that despite 
the final elevation of 100 feet, indicated by the Raised Beaches, ‘‘ the 
promontories, islands, and skerries represent the hill-tops and dividing 
ridges between the drowned valleys.” 
The chapter on economics contains an important account by 
Mr. Maufe of the roofing-slates of Easdale, which have been syste- 
matically worked since 1748. It is interesting to note that while 
most of the best slates are characterized by small cubes of pyrites, 
some of the slates in which the iron sulphides are in a finely 
disseminated state are liable to decay. 
2. THe Grotocy or tHE Sourm Watzs Coat-rrecp. Part I: Tun 
Country arounD Newport, Monmourusuire. By Ausrey Srrawan, 
Se.D., F.R.S. Second Edition. 8vo; pp. x, 115, with 6 text- 
illustrations and 1 plate. London, 1909. Price 1s. 6d. 
\EN years have elapsed since we called attention (Gzot. Mae., 1900, 
p. 86) to the first edition of this memoir, which was also the first 
publication relating to the re-survey of the geology of the South 
Wales Coal-field. “The six- inch survey of the. great coal-field, com- 
menced in 1891, has been conducted and now ‘completed under the 
personal superintendence of Dr. Strahan. 
In this second edition of the Newport memoir the geological infor- 
mation relating to the area has been brought up to date ; and of 
especial importance are the records of new coal-borings. A useful 
map has been added showing thicknesses of the Pennant Grit and 
Lower Coal Series at different localities. 
In the former edition of the memoir attention was called to the 
